Image-guided cerebrospinal fluid shunting in children: catheter accuracy and shunt survival

Improved Accuracy and Lowered Learning Curve of Ventricular Targeting Using Augmented Reality-Phantom and Cadaveric Model Testing

BACKGROUND

Augmented reality (AR) has demonstrated significant potential in neurosurgical cranial, spine, and teaching applications. External ventricular drain (EVD) placement remains a common procedure, but with error rates in targeting between 10% and 40%.

OBJECTIVE

To evaluate Novarad VisAR guidance system for the placement of EVDs in phantom and cadaveric models.

METHODS

Two synthetic ventricular phantom models and a third cadaver model underwent computerized tomography imaging and registration with the VisAR system (Novarad). Root mean square (RMS), angular error (γ), and Euclidian distance were measured by multiple methods for various standard EVD placements.

RESULTS

Computerized tomography measurements on a phantom model (0.5-mm targets showed a mean Euclidean distance error of 1.20 ± 0.98 mm and γ of 1.25° ± 1.02°. Eight participants placed EVDs in lateral and occipital burr holes using VisAR in a second phantom anatomic ventricular model (mean RMS: 3.9 ± 1.8 mm, γ: 3.95° ± 1.78°). There were no statistically significant differences in accuracy for postgraduate year level, prior AR experience, prior EVD experience, or experience with video games ( P > .05). In comparing EVDs placed with anatomic landmarks vs VisAR navigation in a cadaver, VisAR demonstrated significantly better RMS and γ, 7.47 ± 0.94 mm and 7.12° ± 0.97°, respectively ( P ≤ .05).

CONCLUSION

The novel VisAR AR system resulted in accurate placement of EVDs with a rapid learning curve, which may improve clinical treatment and patient safety. Future applications of VisAR can be expanded to other cranial procedures.

Development of an ultrafast brain MR neuronavigation protocol for ventricular shunt placement

OBJECTIVE

Advancements in MRI technology have provided improved ways to acquire imaging data and to more seamlessly incorporate MRI into modern pediatric surgical practice. One such situation is image-guided navigation for pediatric neurosurgical procedures, including intracranial catheter placement. Image-guided surgery (IGS) requires acquisition of CT or MR images, but the former carries the risk of ionizing radiation and the latter is associated with long scan times and often requires pediatric patients to be sedated. The objective of this project was to circumvent the use of CT and standard-sequence MRI in ventricular neuronavigation by investigating the use of fast MR sequences on the basis of 3 criteria: scan duration comparable to that of CT acquisition, visualization of ventricular morphology, and image registration with surface renderings comparable to standard of care. The aim of this work was to report image development, implementation, and results of registration accuracy testing in healthy subjects.

METHODS

The authors formulated 11 candidate MR sequences on the basis of the standard IGS protocol, and various scan parameters were modified, such as k-space readout direction, partial k-space acquisition, sparse sampling of k-space (i.e., compressed sensing), in-plane spatial resolution, and slice thickness. To evaluate registration accuracy, the authors calculated target registration error (TRE). A candidate sequence was selected for further evaluation in 10 healthy subjects.

RESULTS

The authors identified a candidate imaging protocol, termed presurgical imaging with compressed sensing for time optimization (PICO). Acquisition of the PICO protocol takes 25 seconds. The authors demonstrated noninferior TRE for PICO (3.00 ± 0.19 mm) in comparison with the default MRI neuronavigation protocol (3.35 ± 0.20 mm, p = 0.20).

CONCLUSIONS

The developed and tested sequence of this work allowed accurate intraoperative image registration and provided sufficient parenchymal contrast for visualization of ventricular anatomy. Further investigations will evaluate use of the PICO protocol as a substitute for CT and conventional MRI protocols in ventricular neuronavigation.

The effect of image-guided ventricular catheter placement on shunt failure: a systematic review and meta-analysis

INTRODUCTION

Cerebrospinal fluid (CSF) diversion for the treatment of hydrocephalus is one of the most common neurosurgical procedures. Over the years, the development of the neuronavigation system has allowed the surgeon to be guided in real time during the procedures. Nevertheless, to date, the revision rate remains as high as 30-40%. The aim of this study was to investigate the role of intraoperative image guidance in the prevention of shunt failure. We herein report the first literature meta-analysis of image guidance and shunt revision rate in the pediatric population.

METHODS

Principal online databases were searched for English-language articles published between January, 1980, and December, 2021. Analysis was limited to articles that included patients younger than 18 years of age at the time of primary V-P shunt. Articles reporting combined results of free-hand and image-guided placement of ventricular catheter (VC) were included. The main outcome measure of the study was the revision rate in relation to the intraoperative tools. Secondary variables collected were the age of the patient and ventricle size. Statistical analyses and meta-analysis plots were done via R and RStudio. Heterogeneity was formally assessed using Q, I², and τ² statistics. To examine publication bias was performed a funnel plot analysis.

RESULT

A total of 9 studies involving 2017 pediatric patients were included in the meta-analysis. 55.9% of procedures were carried out with the aid of intraoperative tools, while 44.1% procedures were conducted free hand. The intraoperative tools used were ultrasound (9.1%), electromagnetic neuronavigation (21.07%), endoscope (67.32%), and combined images (2.4%).The image-guided placement of VC was not statistically associated with a lower revision rate. The pooled OR was 0.97 [CI 95% 0.88-1.07] with an I² statistics of 34%, t² of 0.018 and a p-value of 0.15 at heterogeneity analysis.

CONCLUSION

Our analysis suggest images guidance during VC shunt placement does not statistically affect shunt survival. Nevertheless, intraoperative tools can support the surgeon especially in patients with difficult anatomy, slit ventricles or complex loculated hydrocephalus.

Cerebrospinal fluid hydrocephalus shunting: cisterna magna, ventricular frontal, ventricular occipital

Despite advances in cerebrospinal fluid shunting technology, complications remain a significant concern. There are some contradictions about the effectiveness of proximal catheter entry sites that decrease shunt failures. We aim to compare efficiency of shunts with ventricular frontal, ventricular occipital, and cisterna magna entry sites. The systemic search was conducted in the database from conception to February 16, 2022 following guidelines of PRISMA. Between 2860 identified articles, 24 articles including 6094 patients were used for data synthesis. The aggregated results of all patients showed that "overall shunt failure rate per year" in mixed hydrocephalus with ventricular frontal and occipital shunts, and cisterna magna shunt (CMS) were 9.0%, 12.6%, and 30.7%, respectively. The corresponding values for "shunt failure rate" due to obstruction were 15.3%, 31.5%, and 10.2%, respectively. The similar results for "shunt failure rate" due to infection were 11.3%, 9.1%, and 27.2%, respectively. The related values for "shunt failure rate" due to overdrainage were 2.9%, 3.9%, and 13.6%, respectively. CMS was successful in the immediate resolution of clinical symptoms. Shunting through an occipital entry site had a greater likelihood of inaccurate catheter placement and location. Contrary to possible shunt failure due to overdrainage, the failure likelihood due to obstruction and infection in pediatric patients was higher than that of mixed hydrocephalus patients. In both mixed and pediatric hydrocephalus, obstruction and overdrainage were the most and least common complications of ventricular frontal and occipital shunts, respectively. The most and least common complications of mixed CMS were infection and obstruction, respectively.

Image-Guided versus Freehand Ventricular Drain Insertion: Systematic Review and Meta-analysis

BACKGROUND

Ventricular drain insertion is a common neurosurgical procedure, typically performed using freehand approach. Use of image-guidance during drain insertion could improve the accuracy and reduce the incidence of drain failure. This review aim to assess the impact of image-guidance on drain placement accuracy, failure rate, and number of ventricular cannulation attempts.

METHODS

MEDLINE, EMBASE and Cochrane Library databases were searched from inception to February 2021 for studies comparing image-guided versus freehand ventricular drain insertion. Two reviewers independently screened studies for eligibility, extracted data, and assessed risk of bias and quality of evidence. Pooled data were reported using random effects model. ROBINS-I tool was used to assess risk of bias and GRADE approach was used to assess quality of evidence.

RESULTS

Of 1102 studies retrieved, 17 were included with a total of 3404 patients. . All included studies were of non-randomized design. Pooled data on drain accuracy and drain failure rates showed favourable effect of image-guidance with risk ratio of 1.31 (95% CI of 1.13 - 1.51, low quality evidence) and 0.63 (95% CI 0.48 - 0.83, moderate quality evidence), respectively. Pooled data were equivocal for number of attempts with mean difference score of -0.11 times (95% CI -0.31 - 0.09, very low-quality evidence). Heterogeneity was substantial for drain accuracy and failure rate outcomes.

CONCLUSIONS

In patients undergoing ventricular drain insertion, the use of image-guidance may enhance drain accuracy and reduce drain failure rate. The use of image-guidance probably does not decrease number of drain insertion attempts.

THE SAFETY AND EFFICACY OF ROBOT-ASSISTED STEREOTACTIC BIOPSY FOR BRAIN GLIOMA: EARLIEST INSTITUTIONAL EXPERIENCES AND EVALUATION OF LITERATURE

Robot-assisted brain tumor biopsy is becoming one of the most important innovative technologies in neurosurgical practice. The idea behind its engagement is to advance the safety and efficacy of the biopsy procedure, which is much in demand when planning the management of endocranial tumor pathology. Herein, we provide our earliest institutional experiences in utilizing this mesmerizing technology. Cranial robotic device was employed for stereotactic robot-assisted brain glioma biopsy in three consecutive patients from our series: an anaplastic isocitrate dehydrogenase (IDH) negative astrocytoma (WHO grade III) located in the right trigone region of the periventricular white matter; a low grade diffuse astrocytoma (WHO grade II) of bilateral thalamic region spreading into the right mesencephalic area; and an IDH-wildtype glioblastoma (WHO grade IV) of the right frontal lobe producing a contralateral midline shifting. Robot-assisted tumor biopsy was successfully performed to get tissue samples for histopathologic and immunohistochemical analysis. The adjacent tissue iatrogenic damage of the eloquent cortical areas was minimal, while the immediate postoperative recovery was satisfactory in all patients. In conclusion, considering the preliminary results of our early experiences, robot-assisted tumor biopsy was proven to be a feasible and accurate procedure when surgery for brain glioma was not an option. It may increase safety and precision, without expanding surgical time, being similarly effective when compared to standard stereotactic and manual biopsy. Using this method to provide accurate sampling for histopathologic and immunohistochemical analysis is a safe and easy way to determine management strategies and outcome of different types of brain glioma.

Freehand stereotactic ventricular catheter insertion for ventriculoperitoneal shunts based on individualized radio-anatomical landmarks

INTRODUCTION

The accurate placement of the ventricular catheter (VC) is critical in reducing the incidence of proximal failure of ventriculoperitoneal shunts (VPSs). The standard freehand technique is based on validated external anatomical landmarks but remains associated with a relatively high rate of VC malposition. Already proposed alternative methods have all their specific limitations. Herein, we evaluate the accuracy of our adapted freehand technique based on an individualized radio-anatomical approach. Reproducing the preoperative imaging on the patient's head using common anatomical landmarks allows to define stereotactic VC coordinates to be followed at surgery.

MATERIAL AND METHODS

Fifty-five consecutive patients treated with 56 VPS between 11/2005 and 02/2020 fulfilled the inclusion criteria of this retrospective study. Burr hole coordinates, VC trajectory, and length were determined in all cases on preoperative computed tomography (CT) scan and were accurately reported on patients' head. The primary endpoint was to evaluate VC placement accuracy. The secondary endpoint was to evaluate the rate and nature of postoperative VC-related complications.

RESULTS

Our new technique was applicable in all patients and no VC-related complications were observed. Postoperative imaging showed VC optimally placed in 85.7% and sub-optimally placed in 14.3% of cases. In all procedures, all the holes on the VC tip were found in the ventricular system.

CONCLUSIONS

This simple individualized technique improves the freehand VC placement in VPS surgery, making its accuracy comparable to that of more sophisticated and expensive techniques. Further randomized controlled studies are required to compare our results with those of the other available techniques.

Free-hand stereotactic ventricular catheter insertion technique based on radio-anatomical landmarks. How I do it

BACKGROUND

Accurate ventricular catheter (VC) placement plays an important role in reducing the risk of ventriculoperitoneal shunt failure. Free-hand VC insertion is associated with a significant misplacement rate. Consequently, several expensive alternative methods that are unfortunately not available worldwide have been used. To overcome these limitations, we developed a simple surgical technique based on radio-anatomical landmarks aimed at reducing VC's misplacements.

METHOD

We reproduce the preoperative imaging on the patient's head using common anatomical landmarks. This allows defining stereotactic VC coordinates to be followed during the surgical procedure.

CONCLUSION

This simple and cost-effective method improves VC insertion accuracy.

Routine postoperative computed tomography scan after craniotomy: systematic review and evidence-based recommendations

Over the last few years, the role of early postoperative computed tomography (EPOCT) after cranial surgery has been repeatedly questioned, but there is yet no consensus on the practice. We conducted a systematic review to address the usefulness of EPOCT in association with neurological examination after elective craniotomies compared to the neurological examination alone. Studies were eligible if they provided information about the number of patients scanned, how many were asymptomatic or presented neurological deterioration before the scan and how many of each of those groups had their management changed due to imaging findings. CTs had to be performed in the first 48 h following surgery to be considered early. Eight studies were included. The retrospective studies enrolled a total of 3639 patients, with 3737 imaging examinations. Out of the 3696 CT scans performed in asymptomatic patients, less than 0.8% prompted an intervention, while 100% of patients with neurological deterioration were submitted to emergency surgery. Positive predictive values of altered scans were 0.584 for symptomatic patients and 0.125 for the asymptomatic. The number of altered scans necessary to predict (NNP) one change in management for the asymptomatic patients was 8, while for the clinically evident cases, it was 1.71. The number of scans needed to diagnose one clinically silent alteration is 134.75, and postoperative imaging of neurologically intact patients is 132 times less likely to issue an emergency intervention than an altered neurological examination alone. EPOCT following elective craniotomy in neurologically preserved patients is not supported by current evidence, and CT scanning should be performed only in particular conditions. The authors have developed an algorithm to help the judgment of each patient by the surgeon in a resource-limited context.

Congress of Neurological Surgeons Systematic Review and Evidence-Based Guidelines on the Treatment of Pediatric Hydrocephalus: Update of the 2014 Guidelines

BACKGROUND

The Congress of Neurological Surgeons reviews its guidelines according to the Institute of Medicine's recommended best practice of reviewing guidelines every 5 yrs. The authors performed a planned 5-yr review of the medical literature used to develop the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines” and determined the need for an update to the original guideline based on new available evidence.

OBJECTIVE

To perform an update to include the current medical literature for the “Pediatric hydrocephalus: systematic literature review and evidence-based guidelines”, originally published in 2014.

METHODS

The Guidelines Task Force used the search terms and strategies consistent with the original guidelines to search PubMed and Cochrane Central for relevant literature published between March 2012 and November 2019. The same inclusion/exclusion criteria were also used to screen abstracts and to perform the full-text review. Full text articles were then reviewed and when appropriate, included as evidence and recommendations were added or changed accordingly.

RESULTS

A total of 41 studies yielded by the updated search met inclusion criteria and were included in this update.

CONCLUSION

New literature resulting from the update yielded a new recommendation in Part 2, which states that neuro-endoscopic lavage is a feasible and safe option for the removal of intraventricular clots and may lower the rate of shunt placement (Level III). Additionally a recommendation in part 7 of the guideline now states that antibiotic-impregnated shunt tubing reduces the risk of shunt infection compared with conventional silicone hardware and should be used for children who require placement of a shunt (Level I). <https://www.cns.org/guidelines/browse-guidelines-detail/pediatric-hydrocephalus-guideline>

Strengths and weaknesses of frontal versus occipital ventriculoperitoneal shunt placement: A systematic review

Excessive accumulation of cerebrospinal fluid within the brain ventricles is called hydrocephalus, which results in increased intracranial pressure preventing brain growth or causing damage to intracranial structures due to raised intracranial pressure. One of the most common treatment options for this pathology includes the placement of a ventriculoperitoneal shunt to drain the excess fluid. The location of catheterization is traditionally considered as an important factor affecting shunt survival. In this study, we aimed to systematically review all available documents to determine the advantage and superiority of frontal or occipital shunt entry points as the two main approaches. A database search was performed in PubMed, Scopus, Embase, Web of Science, Medline, Ovid, and Google Scholar using "ventriculoperitoneal", "shunt placement", and "hydrocephalus" as the main key terms. Resultant articles were screened for relevancy based on predefined inclusion and exclusion criteria by two authors independently. After excluding irrelevant documents, the data of 11 related articles consisting of 3947 patients were extracted and qualitative data synthesis and pooled analysis were performed. The results of the included studies showed that although the outcomes of a higher percentage of the total review population were in favor of frontal shunt placement, there was no significant superiority for neither of these two approaches after pooled analysis of available failure rates. Findings have shown that each approach has benefits and drawbacks, and there may be other factors such as age and valve design besides the position of shunt placement that may affect the survival rate. Also, the accuracy of shunt placement as an independent factor affects the failure rate and can be improved with various image-guidance methods to minimize shunt failure.

Evaluating Shunt Survival Following Ventriculoperitoneal Shunting with and without Stereotactic Navigation in Previously Shunt-Naïve Patients

BACKGROUND

Ventriculoperitoneal shunts are used to alleviate elevated intracranial pressure due to either hydrocephalus or idiopathic intracranial hypertension; however, shunt failure is a significant neurosurgical problem. Despite increases in intraoperative stereotactic navigation usage over the past decade, its effect on shunt survival remains unclear.

METHODS

Shunt-naïve pediatric and adult patients receiving ventriculoperitoneal shunting between 2007 and 2015 were identified in a national administrative database. Multivariable logistic and Cox regressions were used to evaluate factors affecting stereotaxy usage and shunt survival. Matched cohorts were generated by propensity score balancing.

RESULTS

Of 9677 patients identified, 932 received image-guided shunt placement. Total shunt failure rate was not associated with stereotaxy use (20.3% with stereotaxy vs. 19.4% without, P = 0.4602). In the matched setting, shunt survival was not extended by use of image guidance during placement (hazard ratio = 1.134, 95% confidence interval 0.923-1.393). Late shunt failures (defined as failures occurring at least 30 days after shunt placement) caused by infection occurred more frequently in the stereotaxy cohort (hazard ratio = 2.207, 95% confidence interval 1.115-4.366), whereas late shunt failures attributable to mechanical shunt failure were more common in the nonstereotaxy cohort (hazard ratio = 1.406, 95% confidence interval 1.002-1.973).

CONCLUSIONS

Our findings suggest stereotaxy use during ventriculoperitoneal shunt placement does not affect shunt survival. Late shunt failures caused by infection occurred more frequently in the stereotaxy cohort, whereas late failures caused by mechanical shunt malfunction were more commonly encountered in the nonstereotaxy cohort.

Utilizing preprocedural CT scans to identify patients at risk for suboptimal external ventricular drain placement with the freehand insertion technique

OBJECTIVE

Freehand insertion of external ventricular drains (EVDs) using anatomical landmarks is considered the primary method for placement, although alternative techniques have shown improved accuracy in positioning. The purpose of this study was to retrospectively evaluate which features of the baseline clinical history and preprocedural CT scan predict EVD positioning into suboptimal and unsatisfactory locations when using the freehand insertion technique.

METHODS

A retrospective chart review was performed evaluating 189 consecutive adult patients who received an EVD via freehand technique through an anterior burr hole between January 1, 2014, and December 31, 2015, at a Level 1 trauma facility in Edmonton, Alberta, Canada. The primary outcome measures included features associated with suboptimal positioning (Kakarla grade 1 vs Kakarla grades 2 and 3). The secondary outcome measures were features associated with unsatisfactory positioning (Kakarla grades 1 and 2 vs Kakarla grade 3).

RESULTS

Fifty-one EVDs (27%) were suboptimally positioned. Fifteen (8%) EVDs were placed into eloquent cortex or nontarget CSF spaces. Admitting diagnosis, head height-to-width ratio in axial plane, and side of predominant pathology were found to be significantly associated with suboptimal placement (p = 0.02, 0.012, and 0.02, respectively). A decreased height-to-width ratio was also associated with placement into only eloquent cortex and/or nontarget CSF spaces (p = 0.003).

CONCLUSIONS

Freehand insertion of an EVD is associated with significant suboptimal positioning into parenchyma and nontarget CSF spaces. The likelihood of inaccurate EVD placement can be predicted with baseline clinical and radiographic features. The patient's height-to-width ratio represents a novel potential radiographic predictor for malpositioning.

Image Guidance for Ventricular Shunt Surgery: An Analysis of Hospital Charges

BACKGROUND

Image guidance for shunt surgery results in more accurate proximal catheter placement. However, reduction in shunt failure remains unclear in the literature. There have been no prior studies evaluating the cost effectiveness of neuronavigation for shunt surgery.

OBJECTIVE

To perform a cost analysis using available hospital charges of hypothetical shunt surgery performed with/without electromagnetic neuronavigation (EMN).

METHODS

Hospital charges were collected for physician fees, radiology, operating room (OR) time and supplies, postanesthesia care unit, hospitalization days, laboratory, and medications. Index shunt surgery charges (de novo or revision) were totaled and the difference calculated. This difference was compared with hospital charges for shunt revision surgery performed under 2 clinical scenarios: (1) same hospital stay as the index surgery; and (2) readmission through the emergency department.

RESULTS

Costs for freehand de novo and revision shunt surgery were $23 946.22 and $23 359.22, respectively. For stealth-guided de novo and revision surgery, the costs were $33 646.94 and $33 059.94, a difference of $9700.72. The largest charge increase was due to additional OR time (34 min; $4794), followed by disposable EMN equipment ($2672). Total effective charges to revise the shunt for scenarios 1 and 2 were $34 622.94 and $35 934.94, respectively. The cost ratios between the total revision charges for both scenarios and the difference in freehand vs EMN-assisted shunt surgery ($9700.72) were 3.57 and 3.70, respectively.

CONCLUSION

From an economic standpoint and within the limitations of our models, the number needed to prevent must be 4 or less for the use of neuronavigation to be considered cost effective.

Intraoperative Computed Tomography Versus Fluoroscopy for Ventriculoperitoneal Shunt Placement

OBJECTIVE

Catheter malposition represents one of the major causes of ventriculoperitoneal (VP) shunt dysfunction. The usefulness of intraoperative fluoroscopy using skull landmarks has already been proved to decrease catheter malposition and surgical revision rates. After introducing intraoperative computed tomography (iCT) in our department, our objective was to evaluate the accuracy of this imaging modality to decrease cranial catheter misplacement compared with intraoperative fluoroscopy.

METHODS

In our retrospective analysis of 152 patients, catheter placement was evaluated by iCT (n = 48) and biplane fluoroscopy (n = 57). A control group (n = 47) had no intraoperative imaging. Outcome measures included accuracy of ventricular catheter position, revision surgeries, and clinical outcomes.

RESULTS

Ventricular catheter placement was accurate in 24/48 patients with iCT and 45/57 patients with fluoroscopy (P = 0.002) versus 23/47 patients in the control group. Sensitivity and positive predictive value for estimating optimal catheter position with iCT were 100% and 54%. The specificity and negative predictive value were 50% and 100%. After intraoperative revision, 4 catheters remained malpositioned in the iCT group, whereas the fluoroscopy group had none (P = 0.03); 2 of these 4 catheters were revised postoperatively.

CONCLUSIONS

Fluoroscopy may be the method of choice to intraoperatively assess ventricular catheter positioning. In our experience, iCT shows a tendency to be more time consuming and, in the beginning, was not associated with a steeper learning curve. Another consideration was the significant higher radiation exposure per patient. iCT did not improve the accuracy of catheter placement and did not decrease early revisions for VP placement patients.

Placement of Ommaya Reservoirs Using Electromagnetic Neuronavigation and Neuroendoscopy: A Retrospective Study with Cost-Benefit Analysis

BACKGROUND

Placement of intraventricular catheters in oncology patients is associated with high complication rates. Placing Ommaya reservoirs with the zero-error precision protocol (ZEPP), a combination of neuronavigation (AxiEM stereotactic navigation) and direct verification of catheter tip placement with a flexible neuroendoscope, is associated with decreased complication rates as a result of increased catheter placement accuracy. However, the ZEPP costs more than traditional methods of catheter placement, and the question of whether this increased accuracy with the ZEPP is cost-effective is unknown.

METHODS

We performed a single-center retrospective chart review of 50 consecutive ommaya reservoir patient placements between 2010 and 2017. Twenty-five ventricular catheters were placed using the ZEPP protocol, and 25 ventricular catheters were placed using only AxiEM stealth navigation. Postoperative catheter accuracy and complication rates were assessed. A cost-benefit analysis was then conducted to determine if the overall cost for placing Ommaya reservoirs with the ZEPP was effective compared with the alternative method of using neuronavigation alone.

RESULTS

In the non-ZEPP cohort, 10 of 25 catheters were placed within the optimal location compared with 25 of 25 catheters placed in the ZEPP cohort. Three complications occurred in the non-ZEPP cohort: 2 malpositioned catheters required surgical revision and 1 catheter-related hemorrhage resulted in a prolonged stay in the intensive care unit. No complications occurred in the ZEPP cohort. A cost-benefit analysis showed $4784 savings per patient with ZEPP utilization because of the high complication-associated costs.

CONCLUSIONS

Implementation of the ZEPP for verifying ventricular catheter placement in Ommaya reservoirs improved catheter tip accuracy, resulted in lower complication rates, and was more cost-effective when compared with the non-ZEPP cohort, which used only neuronavigation. The ZEPP can be used for ventricular shunt catheter placement to decrease complications and verify catheter tip accuracy in Ommaya or standard ventriculoperitoneal shunts.

Outcome Analysis of Ventriculoperitoneal Shunt Surgery in Pediatric Hydrocephalus

AIM

To study the clinical outcome of shunt surgeries in children with hydrocephalus and evaluate the risk factors for ventriculoperitoneal (VP) shunt failure.

MATERIALS AND METHODS

Patients who underwent VP shunt surgery for hydrocephalus were included. Medical charts, operative reports, imaging studies, and clinical follow-up evaluations were reviewed and analyzed retrospectively.

RESULTS

A total of 137 patients with the average age of 20.7 months, range from 1.5 months to 8.5 years at the time of VP shunt surgery were included. The incidence of overall shunt complications was 35.76%; incidence of shunt revision was 27%, shunt blockade 45.94%, shunt infection 16.21%, shunt migration 10.81%, and shunt malfunction due to abdominal pseudocyst 10.81%. The mortality rate was 5.10%. The shunt revisions in the first 6 months after shunt placement was observed in n = 9 (24%). Hydrocephalus was associated with post-tubercular meningitis and intraventricular hemorrhage (IVH) in shunt placement was associated with multiple shunt revisions (n = 13, 35.13%) (n = 5, 45.4%), respectively.

CONCLUSION

The findings of this study indicate that etiology of hydrocephalus, were associated with the shunt survival. Further prospective controlled studies are required to address the observed associations.

Cerebrospinal Fluid Shunting Complications in Children

Although cerebrospinal fluid (CSF) shunt placement is the most common procedure performed by pediatric neurosurgeons, shunts remain among the most failure-prone life-sustaining medical devices implanted in modern medical practice. This article provides an overview of the mechanisms of CSF shunt failure for the 3 most commonly employed definitive CSF shunts in the practice of pediatric neurosurgery: ventriculoperitoneal, ventriculopleural, and ventriculoatrial. The text has been partitioned into the broad modes of shunt failure: obstruction, infection, mechanical shunt failure, overdrainage, and distal catheter site-specific failures. Clinical management strategies for the various modes of shunt failure are discussed as are research efforts directed towards reducing shunt complication rates. As it is unlikely that CSF shunting will become an obsolete procedure in the foreseeable future, it is incumbent on the pediatric neurosurgery community to maintain focused efforts to improve our understanding of and management strategies for shunt failure and shunt-related morbidity.

The Preventable Shunt Revision Rate: a potential quality metric for pediatric shunt surgery

OBJECTIVE Shunt surgery consumes a large amount of pediatric neurosurgical health care resources. Although many studies have sought to identify risk factors for shunt failure, there is no consensus within the literature on variables that are predictive or protective. In this era of "quality outcome measures," some authors have proposed various metrics to assess quality outcomes for shunt surgery. In this paper, the Preventable Shunt Revision Rate (PSRR) is proposed as a novel quality metric. METHODS An institutional shunt database was queried to identify all shunt surgeries performed from January 1, 2010, to December 31, 2014, at Le Bonheur Children's Hospital. Patients' records were reviewed for 90 days following each "index" shunt surgery to identify those patients who required a return to the operating room. Clinical, demographic, and radiological factors were reviewed for each index operation, and each failure was analyzed for potentially preventable causes. RESULTS During the study period, there were 927 de novo or revision shunt operations in 525 patients. A return to the operating room occurred 202 times within 90 days of shunt surgery in 927 index surgeries (21.8%). In 67 cases (33% of failures), the revision surgery was due to potentially preventable causes, defined as inaccurate proximal or distal catheter placement, infection, or inadequately secured or assembled shunt apparatus. Comparing cases in which failure was due to preventable causes and those in which it was due to nonpreventable causes showed that in cases in which failure was due to preventable causes, the patients were significantly younger (median 3.1 vs 6.7 years, p = 0.01) and the failure was more likely to occur within 30 days of the index surgery (80.6% vs 64.4% of cases, p = 0.02). The most common causes of preventable shunt failure were inaccurate proximal catheter placement (33 [49.3%] of 67 cases) and infection (28 [41.8%] of 67 cases). No variables were found to be predictive of preventable shunt failure with multivariate logistic regression. CONCLUSIONS With economic and governmental pressures to identify and implement "quality measures" for shunt surgery, pediatric neurosurgeons and hospital administrators must be careful to avoid linking all shunt revisions with "poor" or less-than-optimal quality care. To date, many of the purported risk factors for shunt failure and causes of shunt revision surgery are beyond the influence and control of the surgeon. We propose the PSRR as a specific, meaningful, measurable, and-hopefully-modifiable quality metric for shunt surgery in children.

Image Guidance for Placement of Ommaya Reservoirs: Comparison of Fluoroscopy and Frameless Stereotactic Navigation in 145 Patients

OBJECTIVE

Ommaya reservoirs are used for administration of intrathecal chemotherapy and cerebrospinal fluid sampling. Ventricular catheter placement for these purposes requires a high degree of accuracy. Various options exist to optimize catheter placement. We analyze a cohort of patients receiving catheters using 2 different technologies.

METHODS

Retrospective chart review was performed on patients undergoing Ommaya reservoir placement between 2011 and 2014. Most procedures were assisted by either frameless stereotactic neuronavigation or fluoroscopic guidance with pneumoencephalogram. Catheter accuracy, revision rates, perioperative complications, and operative time were measured. Preoperative similarities and differences in diagnosis, demographics, and ventricular size were also recorded to avoid a biased assessment of our results.

RESULTS

One-hundred and forty-five patients were included, 57 using fluoroscopic guidance and 88 using frameless stereotaxy. Common diagnoses in both groups were lymphoma and leptomeningeal disease. Qualitative measures of catheter placement accuracy showed no significant difference between the 2 groups. Proximity to the foramen of Monro favored fluoroscopy by a small margin (8.6 mm vs. 10.2 mm, P = 0.03). Overall revision rates were not significantly different between the groups (3.5% vs. 4.5%, P = 1.00). Early surgical complications occurred in 6.8% of the frameless stereotaxy group and 1.8% of the fluoroscopy group (P = 0.25).

CONCLUSIONS

Ommaya reservoirs can be placed accurately using different methods. Although there are slight differences between fluoroscopy and frameless stereotaxy in quantitative accuracy and procedure time, there is no significant advantage of 1 method over the other when evaluating revision or complication rates. Technique familiarity and surgeon preference may dictate the preferred procedure.

Risk factors for shunt malfunction in pediatric hydrocephalus: a multicenter prospective cohort study

OBJECT The rate of CSF shunt failure remains unacceptably high. The Hydrocephalus Clinical Research Network (HCRN) conducted a comprehensive prospective observational study of hydrocephalus management, the aim of which was to isolate specific risk factors for shunt failure. METHODS The study followed all first-time shunt insertions in children younger than 19 years at 6 HCRN centers. The HCRN Investigator Committee selected, a priori, 21 variables to be examined, including clinical, radiographic, and shunt design variables. Shunt failure was defined as shunt revision, subsequent endoscopic third ventriculostomy, or shunt infection. Important a priori-defined risk factors as well as those significant in univariate analyses were then tested for independence using multivariate Cox proportional hazard modeling. RESULTS A total of 1036 children underwent initial CSF shunt placement between April 2008 and December 2011. Of these, 344 patients experienced shunt failure, including 265 malfunctions and 79 infections. The mean and median length of follow-up for the entire cohort was 400 days and 264 days, respectively. The Cox model found that age younger than 6 months at first shunt placement (HR 1.6 [95% CI 1.1-2.1]), a cardiac comorbidity (HR 1.4 [95% CI 1.0-2.1]), and endoscopic placement (HR 1.9 [95% CI 1.2-2.9]) were independently associated with reduced shunt survival. The following had no independent associations with shunt survival: etiology, payer, center, valve design, valve programmability, the use of ultrasound or stereotactic guidance, and surgeon experience and volume. CONCLUSIONS This is the largest prospective study reported on children with CSF shunts for hydrocephalus. It confirms that a young age and the use of the endoscope are risk factors for first shunt failure and that valve type has no impact. A new risk factor-an existing cardiac comorbidity-was also associated with shunt failure.

Optimizing ventriculoperitoneal shunt placement in the treatment of idiopathic intracranial hypertension: an analysis of neuroendoscopy, frameless stereotaxy, and intraoperative CT

OBJECTIVE

Cerebrospinal fluid shunting can effectively lower intracranial pressure and improve the symptoms of idiopathic intracranial hypertension (IIH). Placement of ventriculoperitoneal (VP) shunts in this patient population can often be difficult due to the small size of the ventricular system. Intraoperative adjuvant techniques can be used to improve the accuracy and safety of VP shunts for these patients. The purpose of this study was to analyze the efficacy of some of these techniques, including the use of intraoperative CT (iCT) and frameless stereotaxy, in optimizing postoperative ventricular catheter placement.

METHODS

The authors conducted a retrospective review of 49 patients undergoing initial ventriculoperitoneal shunt placement for the treatment of IIH. The use of the NeuroPEN Neuroendoscope, intraoperative neuronavigation, and iCT was examined. To analyze ventricular catheter placement on postoperative CT imaging, the authors developed a new grading system: Grade 1, catheter tip terminates optimally in the ipsilateral frontal horn or third ventricle; Grade 2, catheter tip terminates in the contralateral frontal horn; Grade 3, catheter terminates in a nontarget CSF space; and Grade 4, catheter tip terminates in brain parenchyma. All shunts had spontaneous CSF flow upon completion of the procedure.

RESULTS

The average body mass index among all patients was 37.6 ± 10.9 kg/m2. The NeuroPEN Neuroendoscope was used in 44 of 49 patients. Intraoperative CT scans were obtained in 24 patients, and neuronavigation was used in 32 patients. Grade 1 or 2 final postoperative shunt placement was achieved in 90% of patients (44 of 49). In terms of achieving optimal postoperative ventricular catheter placement, the use of iCT was as effective as neuronavigation. Two patients had their ventricular catheter placement modified based on an iCT study. The use of neuronavigation significantly increased time in the operating room (223.4 ± 46.5 vs 190.8 ± 31.7 minutes, p = 0.01). There were no shunt infections in this study.

CONCLUSIONS

The use of iCT appears to be equivalent to the use of neuronavigation in optimizing ventricular shunt placement in IIH. Additionally, it may shorten operating room time and limit overall costs.

Predicting shunt failure in children: should the global shunt revision rate be a quality measure?

OBJECT

Ventricular shunts for pediatric hydrocephalus continue to be plagued with high failure rates. Reported risk factors for shunt failure are inconsistent and controversial. The raw or global shunt revision rate has been the foundation of several proposed quality metrics. The authors undertook this study to determine risk factors for shunt revision within their own patient population.

METHODS

In this single-center retrospective cohort study, a database was created of all ventricular shunt operations performed at the authors' institution from January 1, 2010, through December 2013. For each index shunt surgery, demographic, clinical, and procedural variables were assembled. An "index surgery" was defined as implantation of a new shunt or the revision or augmentation of an existing shunt system. Bivariate analyses were first performed to evaluate individual effects of each independent variable on shunt failure at 90 days and at 180 days. A final multivariate model was chosen for each outcome by using a backward model selection approach.

RESULTS

There were 466 patients in the study accounting for 739 unique ("index") operations, for an average of 1.59 procedures per patient. The median age for the cohort at the time of the first shunt surgery was 5 years (range 0-35.7 years), with 53.9% males. The 90- and 180-day shunt failure rates were 24.1% and 29.9%, respectively. The authors found no variable-demographic, clinical, or procedural-that predicted shunt failure within 90 or 180 days.

CONCLUSIONS

In this study, none of the risk factors that were examined were statistically significant in determining shunt failure within 90 or 180 days. Given the negative findings and the fact that all other risk factors for shunt failure that have been proposed in the literature thus far are beyond the control of the surgeon (i.e., nonmodifiable), the use of an institution's or individual's global shunt revision rate remains questionable and needs further evaluation before being accepted as a quality metric.

Proximal ventricular shunt malfunctions in children: Factors associated with failure

Ventricular shunt failures and subsequent revisions are a significant source of patient morbidity. We conducted a review of pediatric patients undergoing placement or revision of ventricular shunts at our institution between January 2007 and December 2008. Patients were followed through to July 2014. Data collected included patient demographics, shunt history and indication for procedure, approach taken for shunt placement, and location of shunt tip in relation to the foramen of Monro. Univariate and multivariate analyses were conducted to identify factors associated with proximal failure. A total of 87 procedures were identified in 40 patients, consisting of 23 initial placements and 64 revisions. Thirty-nine proximal catheter malfunctions were identified. Indications for shunt placement included Chiari II malformation (33%) and intraventricular hemorrhage (33%). Mean follow-up period was 5.5 years. Median time to shunt failure was 1.57 years. In the multivariate model, younger age at placement was associated with decreased time to proximal failure (hazard ratio [HR]=0.80 per increasing year of age, 95% confidence interval [CI] 0.64-0.98). Both anterior approach (HR=0.39, 95% CI 0.23-0.67) and farther distance to foramen of Monro (HR=0.02 per increasing 10mm, 95% CI 0.00-0.22) were associated with increased time to proximal failure when the catheter tip was located within the contralateral lateral ventricle. Optimizing outcomes in patients with shunt-dependent hydrocephalus continues to be a challenge. Despite unsatisfactory outcomes, particularly in the pediatric population, few conclusions can be drawn from studies assessing operative variables.

Ultrasound stylet for non-image-guided ventricular catheterization

OBJECT Urgent ventriculostomy placement can be a lifesaving procedure in the setting of hydrocephalus or elevated intracranial pressure. While external ventricular drain (EVD) insertion is common, there remains a high rate of suboptimal drain placement. Here, the authors seek to demonstrate the feasibility of an ultrasound-based guidance system that can be inserted into an existing EVD catheter to provide a linear ultrasound trace that guides the user toward the ventricle. METHODS The ultrasound stylet was constructed as a thin metal tube, with dimensions equivalent to standard catheter stylets, bearing a single-element, ceramic ultrasound transducer at the tip. Ultrasound backscatter signals from the porcine ventricle were processed by custom electronics to offer real-time information about ventricular location relative to the catheter. Data collected from the prototype device were compared with reference measurements obtained using standard clinical ultrasound imaging. RESULTS A study of porcine ventricular catheterization using the experimental device yielded a high rate of successful catheter placement after a single pass (10 of 12 trials), despite the small size of pig ventricles and the lack of prior instruction on porcine ventricular architecture. A characteristic double-peak signal was identified, which originated from ultrasound reflections off of the near and far ventricular walls. Ventricular dimensions, as obtained from the width between peaks, were in agreement with standard ultrasound reference measurements (p < 0.05). Furthermore, linear ultrasound backscatter data permitted in situ measurement of the stylet distance to the ventricular wall (p < 0.05), which assisted in catheter guidance. CONCLUSIONS The authors have demonstrated the ability of the prototype ultrasound stylet to guide ventricular access in the porcine brain. The alternative design of the device makes it potentially easy to integrate into the standard workflow for bedside EVD placement. The availability of a fast, easy-to-use, inexpensive guidance system can play a role in reducing the complication rate for EVD placement.

Intraoperative Fluoroscopy for Ventriculoperitoneal Shunt Placement

OBJECTIVE

Catheter malpositioning is one of the most frequent causes of ventriculoperitoneal shunt dysfunction and revision surgery. Most intraoperative tools used to improve the accuracy of catheter insertion are time consuming and expensive or do not display the final position. We evaluate the usefulness of intraoperative fluoroscopy to decrease catheter malpositioning, and define radiological landmarks to identify the correct localization.

METHODS

A total of 104 patients undergoing ventriculoperitoneal shunt placement were analyzed for shunt position, revision surgery and outcome. The results for patients operated on using intraoperative biplanar fluoroscopic assessment of catheter location (X-ray group, n = 57) were compared with a control group operated without intraoperative radiography (control, n = 47). In order to generate a surgical reference map for intraoperative validation of shunt location, different ventricular system landmarks were defined on three-dimensional computed tomography reconstructions of hydrocephalic patients (n = 60) and exported to a two-dimensional layer of the skull.

RESULTS

The use of intraoperative X-ray imaging correlated with a significant increase of optimal catheter positions (X-ray group, n = 45, 79%; control group, n = 23, 49%; P = 0.0018). The sensitivity and positive predictive value for estimating an optimal shunt catheter position on biplanar imaging was 96% (95% confidence interval, 87%-99%). The specificity and negative predictive value were both 92% (95% confidence interval, 78%-98%).

CONCLUSIONS

Intraoperative fluoroscopy is easy to perform and is a reliable method to assess correct catheter positioning. Based on its predictive value, corrections of malpositioned ventricular catheters can be performed during the same procedure. The use of intraoperative fluoroscopy decreases early surgical revisions in ventriculoperitoneal shunt treatment.

Endoscopic intracranial surgery enhanced by electromagnetic-guided neuronavigation in children

PURPOSE

Navigated intracranial endoscopy with conventional technique usually requires sharp head fixation. In children, especially in those younger than 1 year of age and in older children with thin skulls due to chronic hydrocephalus, sharp head fixation is not possible. Here, we studied the feasibility, safety, and accuracy of electromagnetic (EM)-navigated endoscopy in a series of children, obviating the need of sharp head fixation.

METHODS

Seventeen children (ten boys, seven girls) between 12 days and 16.8 years (mean age 4.3 years; median 14 months) underwent EM-navigated intracranial endoscopic surgery based on 3D MR imaging of the head. Inclusion criteria for the study were intraventricular cysts, arachnoid cysts, aqueduct stenosis for endoscopic third ventriculostomy (ETV) with distorted ventricular anatomy, the need of biopsy in intraventricular tumors, and multiloculated hydrocephalus. A total of 22 endoscopic procedures were performed. Patients were registered for navigation by surface rendering in the supine position. After confirming accuracy, they were repositioned for endoscopic surgery with the head fixed slightly on a horseshoe headholder. EM navigation was performed using a flexible stylet introduced into the working channel of a rigid endoscope. Neuronavigation accuracy was checked for deviations measured in millimeters on screenshots after the referencing procedure and during surgery in the coronal (z = vertical), axial (x = mediolateral), and sagittal (y = anteroposterior) planes.

RESULTS

EM-navigated endoscopy was feasible and safe. In all 17 patients, the aim of endoscopic surgery was achieved, except in one case in which a hemorrhage occurred, blurring visibility, and we proceeded with open surgery without complications for the patient. Navigation accuracy for extracranial markers such as the tragus, bregma, and nasion ranged between 1 and 2.5 mm. Accuracy for fixed anatomical structures like the optic nerve or the carotid artery varied between 2 and 4 mm, while there was a broader variance of accuracy at the target point of the cyst itself ranging between 2 and 9 mm.

CONCLUSIONS

EM-navigated endoscopy in children is a safe and useful technique enhancing endoscopic intracranial surgery and obviating the need of sharp head fixation. It is a good alternative to the common opto-electric navigation system in this age group.

An update on research priorities in hydrocephalus: overview of the third National Institutes of Health-sponsored symposium "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes"

Building on previous National Institutes of Health-sponsored symposia on hydrocephalus research, "Opportunities for Hydrocephalus Research: Pathways to Better Outcomes" was held in Seattle, Washington, July 9-11, 2012. Plenary sessions were organized into four major themes, each with two subtopics: Causes of Hydrocephalus (Genetics and Pathophysiological Modifications); Diagnosis of Hydrocephalus (Biomarkers and Neuroimaging); Treatment of Hydrocephalus (Bioengineering Advances and Surgical Treatments); and Outcome in Hydrocephalus (Neuropsychological and Neurological). International experts gave plenary talks, and extensive group discussions were held for each of the major themes. The conference emphasized patient-centered care and translational research, with the main objective to arrive at a consensus on priorities in hydrocephalus that have the potential to impact patient care in the next 5 years. The current state of hydrocephalus research and treatment was presented, and the following priorities for research were recommended for each theme. 1) Causes of Hydrocephalus-CSF absorption, production, and related drug therapies; pathogenesis of human hydrocephalus; improved animal and in vitro models of hydrocephalus; developmental and macromolecular transport mechanisms; biomechanical changes in hydrocephalus; and age-dependent mechanisms in the development of hydrocephalus. 2) Diagnosis of Hydrocephalus-implementation of a standardized set of protocols and a shared repository of technical information; prospective studies of multimodal techniques including MRI and CSF biomarkers to test potential pharmacological treatments; and quantitative and cost-effective CSF assessment techniques. 3) Treatment of Hydrocephalus-improved bioengineering efforts to reduce proximal catheter and overall shunt failure; external or implantable diagnostics and support for the biological infrastructure research that informs these efforts; and evidence-based surgical standardization with longitudinal metrics to validate or refute implemented practices, procedures, or tests. 4) Outcome in Hydrocephalus-development of specific, reliable batteries with metrics focused on the hydrocephalic patient; measurements of neurocognitive outcome and quality-of-life measures that are adaptable, trackable across the growth spectrum, and applicable cross-culturally; development of comparison metrics against normal aging and sensitive screening tools to diagnose idiopathic normal pressure hydrocephalus against appropriate normative age-based data; better understanding of the incidence and prevalence of hydrocephalus within both pediatric and adult populations; and comparisons of aging patterns in adults with hydrocephalus against normal aging patterns.

Image Guidance in Ventricular Cerebrospinal Fluid Shunt Catheter Placement

BACKGROUND:

Ventricular shunt placement for treating hydrocephalus is one of the most common neurosurgical procedures. The rate of shunt failure, however, has not appreciably changed with time.

OBJECTIVE:

To investigate whether intraoperative image guidance using ultrasound or stereotaxy contributes to accurate shunt catheter placement and survival.

METHODS:

We performed a systematic literature review using PubMed and MEDLINE databases for studies that use ultrasound and frameless stereotaxy for ventricular catheter placement for hydrocephalus. All articles assessed the accuracy of catheter tip placement and/or overall shunt survival, and the rate of accurate shunt catheter placement, the overall failure rate, and the average time to shunt failure were extracted for analysis.

RESULTS:

Although each modality (ultrasound/stereotaxy) did not increase catheter placement accuracy, a combined random-effects meta-analysis of 738 catheters (136 guided by ultrasound, 168 guided by frameless stereotaxy, and 434 freehand) demonstrated a weak benefit of image guidance (risk ratio: 1.19, 95% confidence interval: 1.02-1.39, P = .02), but this result was limited by considerable heterogeneity among studies (I2 = 86%, P &lt; .001 by Cochrane's Q test). A meta-analysis could not be performed for shunt survival due to heterogeneity in data reporting.

CONCLUSION:

Although image guidance offers a promising solution to lower the risk of inaccurate catheter placement, which could lead to lower premature failure of ventricular shunts, our review demonstrated that there is not yet a clear benefit of these technologies. Current literature is limited to case series and cohort studies, and significant between-study heterogeneity in methodology and reporting currently limits a higher order analysis.

A Retrospective Analysis of Ventriculoperitoneal Shunt Revision Cases of a Single Institute

Objective

Ventriculoperitoneal (VP) shunt complication is a major obstacle in the management of hydrocephalus. To study the differences of VP shunt complications between children and adults, we analyzed shunt revision surgery performed at our hospital during the past 10 years.

Methods

Patients who had undergone shunt revision surgery from January 2001 to December 2010 were evaluated retrospectively by chart review about age distribution, etiology of hydrocephalus, and causes of revision. Patients were grouped into below and above 20 years old.

Results

Among 528 cases of VP shunt surgery performed in our hospital over 10 years, 146 (27.7%) were revision surgery. Infection and obstruction were the most common causes of revision. Fifty-one patients were operated on within 1 month after original VP shunt surgery. Thirty-six of 46 infection cases were operated before 6 months after the initial VP shunt. Incidence of shunt catheter fracture was higher in younger patients compared to older. Two of 8 fractured catheters in the younger group were due to calcification and degradation of shunt catheters with fibrous adhesion to surrounding tissue.

Conclusion

The complications of VP shunts were different between children and adults. The incidence of shunt catheter fracture was higher in younger patients. Degradation of shunt catheter associated with surrounding tissue calcification could be one of the reasons of the difference in facture rates.

Real-time ultrasound guidance for ventricular catheter placement in pediatric cerebrospinal fluid shunts

PURPOSE

Cerebrospinal fluid shunt failure is related to additional morbidity. Misplacement of ventricular catheters occurs in 40 % with freehand technique and is a risk factor for shunt failure. The goal of this study was to analyze the impact of intraoperative real-time ultrasound on catheter positioning and outcome in children.

METHODS

We compared children receiving ultrasound-guided procedures to matched historical freehand controls. Burr hole and convex probes were used (ProSound Alpha 6, Hitachi Aloka Medical Ltd., Tokyo, Japan). Catheter position was graded as grade I (optimal), II (contralateral ventricle or contact with ventricular structures), or III (misplacement). Correlation analysis was performed to identify determinants of outcome.

RESULTS

The study group (n = 17) was balanced with the control group (n = 14) for variables such as mean age (4.7 vs 4.3 years) and preoperative frontal occipital horn ratio (FOHR; 0.45 vs 0.43). In the study group, grade I catheter position was achieved in 6 (35%) and grade II in 11 patients (65%), compared to 2 (18%) and 3 patients (27%) in the control group. While no grade III position occurred in the study group, it was found in nine control patients (43%) (P = 0.0029). Failure rate was highest in grade III (83%) compared to grade I catheters (50%).

CONCLUSIONS

This analysis demonstrated an improvement of catheter positioning with ultrasound guidance. In the absence of additional burden or risks, this method should be favored over freehand technique. It remains to be demonstrated in a randomized controlled fashion to what extent improved catheter position translates into improved outcome.

Pediatric hydrocephalus: systematic literature review and evidence-based guidelines. Part 3: Endoscopic computer-assisted electromagnetic navigation and ultrasonography as technical adjuvants for shunt placement

OBJECT

This systematic review was undertaken to answer the following question: Do technical adjuvants such as ventricular endoscopic placement, computer-assisted electromagnetic guidance, or ultrasound guidance improve ventricular shunt function and survival?

METHODS

The US National Library of Medicine PubMed/MEDLINE database and the Cochrane Database of Systematic Reviews were queried using MeSH headings and key words specifically chosen to identify published articles detailing the use of cerebrospinal fluid shunts for the treatment of pediatric hydrocephalus. Articles meeting specific criteria that had been delineated a priori were then examined, and data were abstracted and compiled in evidentiary tables. These data were then analyzed by the Pediatric Hydrocephalus Systematic Review and Evidence-Based Guidelines Task Force to consider evidence-based treatment recommendations.

RESULTS

The search yielded 163 abstracts, which were screened for potential relevance to the application of technical adjuvants in shunt placement. Fourteen articles were selected for full-text review. One additional article was selected during a review of literature citations. Eight of these articles were included in the final recommendations concerning the use of endoscopy, ultrasonography, and electromagnetic image guidance during shunt placement, whereas the remaining articles were excluded due to poor evidence or lack of relevance. The evidence included 1 Class I, 1 Class II, and 6 Class III papers. An evidentiary table of relevant articles was created. CONCLUSIONS/RECOMMENDATION: There is insufficient evidence to recommend the use of endoscopic guidance for routine ventricular catheter placement.

STRENGTH OF RECOMMENDATION

Level I, high degree of clinical certainty.

RECOMMENDATION

The routine use of ultrasound-assisted catheter placement is an option.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty.

RECOMMENDATION

The routine use of computer-assisted electromagnetic (EM) navigation is an option.

STRENGTH OF RECOMMENDATION

Level III, unclear clinical certainty.

Non-assisted versus neuro-navigated and XperCT-guided external ventricular catheter placement: a comparative cadaver study

BACKGROUND AND PURPOSE

Accurate placement of an external ventricular drain (EVD) for the treatment of hydrocephalus is of paramount importance for its functionality and in order to minimize morbidity and complications. The aim of this study was to compare two different drain insertion assistance tools with the traditional free-hand anatomical landmark method, and to measure efficacy, safety and precision.

METHODS

Ten cadaver heads were prepared by opening large bone windows centered on Kocher's points on both sides. Nineteen physicians, divided in two groups (trainees and board certified neurosurgeons) performed EVD insertions. The target for the ventricular drain tip was the ipsilateral foramen of Monro. Each participant inserted the external ventricular catheter in three different ways: 1) free-hand by anatomical landmarks, 2) neuronavigation-assisted (NN), and 3) XperCT-guided (XCT). The number of ventricular hits and dangerous trajectories; time to proceed; radiation exposure of patients and physicians; distance of the catheter tip to target and size of deviations projected in the orthogonal plans were measured and compared.

RESULTS

Insertion using XCT increased the probability of ventricular puncture from 69.2 to 90.2 % (p = 0.02). Non-assisted placements were significantly less precise (catheter tip to target distance 14.3 ± 7.4 mm versus 9.6 ± 7.2 mm, p = 0.0003). The insertion time to proceed increased from 3.04 ± 2.06 min. to 7.3 ± 3.6 min. (p < 0.001). The X-ray exposure for XCT was 32.23 mSv, but could be reduced to 13.9 mSv if patients were initially imaged in the hybrid-operating suite. No supplementary radiation exposure is needed for NN if patients are imaged according to a navigation protocol initially.

CONCLUSION

This ex vivo study demonstrates a significantly improved accuracy and safety using either NN or XCT-assisted methods. Therefore, efforts should be undertaken to implement these new technologies into daily clinical practice. However, the accuracy versus urgency of an EVD placement has to be balanced, as the image-guided insertion technique will implicate a longer preparation time due to a specific image acquisition and trajectory planning.

Validation of model-guided placement of external ventricular drains

PURPOSE

Inaccurate placement of external ventricular drains (EVDs) is a common issue in cerebrospinal diversion procedures. The conventional freehand technique results in a high fraction of sub-optimally placed catheters, and the use of image guidance can improve these results. The purpose of this paper is the validation of the use of an average model for guidance of EVD procedures.

METHODS

Three neurosurgeons have tested the model-based technique on three normal volunteers, and we have compared the model-based technique to the freehand technique and neuronavigation based on volunteer-specific images.

RESULTS

Our results show that the surgeons perform significantly better when using the model-based technique than when using the freehand technique.

CONCLUSIONS

Our results suggest that the use of an average model may improve the accuracy of catheter placements. However, further refinement of the method and testing in a clinical setting is required.

Low-dose head computed tomography in children: a single institutional experience in pediatric radiation risk reduction: clinical article

OBJECT

In this study, the authors describe their experience with a low-dose head CT protocol for a preselected neurosurgical population at a dedicated pediatric hospital (Seattle Children's Hospital), the largest number of patients with this protocol reported to date.

METHODS

All low-dose head CT scans between October 2011 and November 2012 were reviewed. Two different low-dose radiation dosages were used, at one-half or one-quarter the dose of a standard head CT scan, based on patient characteristics agreed upon by the neurosurgery and radiology departments. Patient information was also recorded, including diagnosis and indication for CT scan.

RESULTS

Six hundred twenty-four low-dose head CT procedures were performed within the 12-month study period. Although indications for the CT scans varied, the most common reason was to evaluate the ventricles and catheter placement in hydrocephalic patients with shunts (70%), followed by postoperative craniosynostosis imaging (12%). These scans provided adequate diagnostic imaging, and no patient required a follow-up full-dose CT scan as a result of poor image quality on a low-dose CT scan. Overall physician comfort and satisfaction with interpretation of the images was high. An additional 2150 full-dose head CT scans were performed during the same 12-month time period, making the total number of CT scans 2774. This value compares to 3730 full-dose head CT scans obtained during the year prior to the study when low-dose CT and rapid-sequence MRI was not a reliable option at Seattle Children's Hospital. Thus, over a 1-year period, 22% of the total CT scans were able to be converted to low-dose scans, and full-dose CT scans were able to be reduced by 42%.

CONCLUSIONS

The implementation of a low-dose head CT protocol substantially reduced the amount of ionizing radiation exposure in a preselected population of pediatric neurosurgical patients. Image quality and diagnostic utility were not significantly compromised.

Image-guided implantation of pre-calibrated catheters in the ICU: a feasibility study

BACKGROUND

Image-guided implantation of intracranial catheters is a routine procedure. Although time for surgery is short, transport from the intensive care unit (ICU) to the operation room (OR) is time-consuming and endangers patients in vulnerable intracranial pressure phases. Unfortunately, technical aspects of image guidance have so far required surgery to be performed in the operation room. In this observational study we investigated the feasibility of image-guided catheter placement in the ICU using a pre-calibrated stylet for implantation of intracranial catheters for a variety of indications and compare the results of procedures performed in the OR.

METHODS

Twenty-three patients received implantation of 31 image-guided intracranial catheters or external ventricular drains using a pre-calibrated stylet in the ICU or in the OR. The times required for navigation planning, transport and surgery were assessed. Pre-operative trajectory planning, intra-operative screenshots of the navigation system and postoperative computed tomography (CT) scans were compared.

RESULTS

Eleven external ventricular drains and nine intracranial catheters for fibrinolytic therapy of intracerebral haemorrhage were implanted in the OR, whereas ten external ventricular drains and one catheter for fibrinolytic therapy were implanted in the ICU. All catheters implanted on the ICU, 81.8 % of external ventricular drains and 88.8 % of lysis catheters placed in the OR had an optimal position to function.

CONCLUSION

A pre-calibrated stylet in combination with the flexible headband equipped with reference arrays allows the application of image guidance in the ICU. It reduced time expended for patients and employees, and avoided the risks of ICU transport to the OR.